nontransactional dml FAQ about alias (#22523)#22535
nontransactional dml FAQ about alias (#22523)#22535ti-chi-bot[bot] merged 2 commits intopingcap:release-6.5from
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Summary of ChangesHello, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request enhances the TiDB documentation by addressing a common Highlights
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Code Review
This pull request adds a new FAQ section to the non-transactional DML documentation, explaining a potential Unknown column error when using table aliases. It also adds a note about this issue to the BATCH statement documentation. The changes are clear and helpful for users. I've provided a couple of minor suggestions to improve the wording for better clarity and conciseness, following the repository's documentation style guide.
Note: Security Review has been skipped due to the limited scope of the PR.
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| When you execute a non-transactional DML statement, TiDB internally constructs a query for dividing batches and then generates the actual split execution statements. You can use [`DRY RUN QUERY`](/non-transactional-dml.md#query-the-batch-dividing-statement) and [`DRY RUN`](/non-transactional-dml.md#query-the-statements-corresponding-to-the-first-and-the-last-batches) to view these two types of statements, respectively. | ||
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| In the current version, the rewritten statements might not preserve the table aliases from the original DML statement. Therefore, if you use the `<alias>.<column>` format to reference columns in a `WHERE` clause or other expressions, an `Unknown column` error might occur. |
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This sentence can be rephrased for better clarity and conciseness, and to remove the vague phrase 'In the current version'.
| In the current version, the rewritten statements might not preserve the table aliases from the original DML statement. Therefore, if you use the `<alias>.<column>` format to reference columns in a `WHERE` clause or other expressions, an `Unknown column` error might occur. | |
| Because the rewritten statements might not preserve the table aliases from the original DML statement, you might get an `Unknown column` error if you use the `<alias>.<column>` format to reference columns in a `WHERE` clause or other expressions. |
References
- The style guide recommends writing in the second person ('you'), avoiding unnecessary words, and being direct. This suggestion rephrases the sentence to be more active and concise, removing the vague phrase 'In the current version'. (link)
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| > **Note:** | ||
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| > The `BATCH` statement is internally rewritten and split into multiple DML statements during execution. In the current version, table aliases might not be preserved, which can result in errors such as `Unknown column '<alias>.<column>' in 'where clause'`. To avoid this issue, do not use table aliases. Before execution, use `DRY RUN QUERY` or `DRY RUN` to preview the split statements before execution. For more information, see [Non-Transactional DML Statements](/non-transactional-dml.md). |
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This note can be improved for clarity and conciseness. The phrase 'In the current version' is vague, and 'before execution' is repeated. This suggestion rephrases the note to be more direct and easier to read.
| > The `BATCH` statement is internally rewritten and split into multiple DML statements during execution. In the current version, table aliases might not be preserved, which can result in errors such as `Unknown column '<alias>.<column>' in 'where clause'`. To avoid this issue, do not use table aliases. Before execution, use `DRY RUN QUERY` or `DRY RUN` to preview the split statements before execution. For more information, see [Non-Transactional DML Statements](/non-transactional-dml.md). | |
| > The `BATCH` statement is internally rewritten and split into multiple DML statements during execution. These rewritten statements might not preserve table aliases, which can result in errors such as `Unknown column '<alias>.<column>' in 'where clause'`. To avoid this issue, do not use table aliases. You can use `DRY RUN QUERY` or `DRY RUN` to preview the split statements before execution. For more information, see [Non-Transactional DML Statements](/non-transactional-dml.md). |
References
- The style guide recommends avoiding unnecessary words and repetition. This suggestion removes the repeated phrase 'before execution' and the vague phrase 'In the current version' to improve readability and conciseness. (link)
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/approve |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: Oreoxmt The full list of commands accepted by this bot can be found here. The pull request process is described here DetailsNeeds approval from an approver in each of these files:
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This is an automated cherry-pick of #22523
First-time contributors' checklist
What is changed, added or deleted? (Required)
Added FAQ about
Unknown columnerror when using alias.Which TiDB version(s) do your changes apply to? (Required)
Tips for choosing the affected version(s):
By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.
For details, see tips for choosing the affected versions (in Chinese).
What is the related PR or file link(s)?
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